A tremolo having such an angled pivoting axis is known from U.S. Pat. No. 4,632,005. This known tremolo consists of a bridge to which several roller-equipped saddles are mounted, which bridge is firmly mounted to the body of the stringed instrument, and a tailpiece pivotable about a fixed angled pivoting axis, to which tailpiece the strings are anchored.
The string tension of the plurality of strings is in balance about the pivoting axis with a tremolo spring, whereas the tremolo is activated by exercising a pulling or pushing force on a lever (hereinafter referred to as: tremolo-arm). So, the tailpiece pivots and a corresponding increment or decrement of the tension and the pitch of each string is achieved, the strings moving on rollers in the saddles. The movement of strings on the rollers can cause friction, particularly when wear and corrosion occur in the bearing of these rollers. Moreover, the bearing of the pivoting axis in the known tremolo comprises an axis and a hole. It is known that such a bearing has much more friction than for instance a knife edge bearing. Furthermore, the known apparatus is equipped with a compression type coil spring as tremolo spring, which about an arm counter-balances the string tension. This construction is not statically determined, so that undesired deformation and friction can occur.
The occurrence of friction in the tremolo movement is a problem, because the tremolo will not always return to the same neutral position, causing the stringed instrument to sound out of tune.
In addition, the angle of the pivoting axis is determined, so that it is hardly possible to set the amount of pushing or pulling force on the tremolo arm relative to the tremolo effect (hereafter referred to as: tremolo action) precise and within an adequate range. Particularly, when using a heavier string gauge the action of the known tremolo cannot be set deep enough.
The known tremolo further is supplied with the feature that the distance between the anchoring point of each string and the pivoting axis can be adjusted in order to facilitate a very precise compensation of the different stretch characteristics of each string, with the objective to maintain the relative tonal intervals between the strings when using the tremolo.
When adjusting to the exact stretch characteristics the problem occurs that it is very difficult to achieve any sensible adjustment, for instance, when mounting a different string type. Also the stretch characteristics of the strings change rather quick due to aging and loss of elasticity.
This known tremolo apparatus is only suitable for guitars with an open back, in which at the rear side, viewed from the neck of a stringed instrument, no part of the body may be found.
To manufacture a working version of this known tremolo, a complex, expensive and bulky construction is necessary.